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MathGroup Archive 2001

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Re: Decimal math bug?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg28786] Re: Decimal math bug?
  • From: Jim Freeze <jim at freeze.org>
  • Date: Sat, 12 May 2001 20:18:19 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

On Sat, 12 May 2001, Steven M. Christensen wrote:


This looks like a bug.
Can someone please explain.

This is Mathematica 4.1 (just purchased) on Linux.

In[88]:=(.53+.9) - (1.43) == 0
Out[88]:=False
---------^^^^^

In[89]:=(.53+.9) - (.43+1.0)== 0
Out[89]:=False
---------^^^^^

In[100]:=(.53+.9) - (.43+0.8+0.2) == 0
Out[100]:=False
----------^^^^^

In[102]:=(.53+.9) - (.43+0.8+0.1 +0.1) == 0
Out[102]:=True
----------^^^^

The above results from some strange decimal math:
In[67]:=Range[.53,4,.9]
Out[103]:={0.53, 1.4300000000000002, 2.33, 3.23}

where sometimes 1.4300000000000002 == 1.43 and sometimes
it doesn't.

It is really disconcerting to have that trailing 2.

Can someone please explain what is going on here?

Thanks
=========================================================
Jim Freeze
jim at freeze.org
---------------------------------------------------------
No comment at this time.
http://www.freeze.org
=========================================================


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